Method of and apparatus for testing platinum alloys



June 17 ,1924. 1,498,073

A. col-IN METHOD OF AND APPARATUS FOR TESTING PLATINUM ALLOYS Filed Dec.27. 1923 A DOLPH CUf//V ATTORNEY Patented June 17, 1924 1,498,073vUruTED STATES PATENT oFElcE-.

ADLP COHN, OF NEW YORK, N. Y.

METHOD 0F AN D APPARATUS FOR TESTING PLATINUM ALLQYS.

Application led December 27, 1923. Serial No. 682,871.

To all whom z't may comer/n.'

Be it known that I, ADOLPH CoHN, a citizen of the United States, and aresident of New York city, State `and county of New York', have inventedcertain new and useful Improvements in Methods of and Apparatus forTesting Platinum Alloys, of which the following is a specification.

This invention relates to methods of and means for testing the purity ofplatinum alloys.

As is well known in the'arts gold has been tested for purity bycomparing the intensity of marks made by rubbing a sample of gold alloyof unknown composition with similar marks made with gold alloy `of knowncomposition, after such'marks have been made on black colored stone andtreated by the application of nitric acid, which has the property ofdissolving the metals which are alloyed with the gold and leaving thegold untouched. rlhis method as carriedout in testing the purity of goldor gold alloys is not applicable in testing the purity of platinumalloys.

The present invention has for. its salient object the provision of amethod and of apparatus for testingv the purity of platinum alloys andis based on the fact that different alloys of platinum dissolve incertain liquids at varying rates of speed, and that the rate of speed'ofdissolution varies directly with the percentage of purity of theplatinum. That is, the higherv the' percentage of pure platinum, theslower will be the speed of dissolution. v

Further objects of the invention will appear from the followingspecification taken in connection with the drawin which form a part ofthis application, an in which,

Fig. 1 is a perspective view showing apparatus in use in carrying outthe method.

Fig. 2 is an elevational view showing one manner of mounting a pluralityof samples of platinum alloys of different compositions, and

Fig. 3 is a view taken at right angles to F ig. 2 and partly in sectionshowing the mounting of vthe samples. Y

The invention brielly described consists in makin scratch marks on acomparatively smooth, at, dark stone or artificial int block or othersuitable substances not subject to acid action, applying amixture ofnitric and muriatic acids, preferably in sub- Stantially equal amounts,to the marks and heating the stone to facilitate the action of the acid.The temperature to which the stone is heated should be below the boilingpoint of the acid. By using a plurality of di'erent platinum alloys inconjunction with the alloy to be tested, the degree of purity of thealloy to be tested can be determined since certain platinum alloysdissolve much more quickly than other alloys. Further details of theinvention will appear from the following description.

Referrin tothe drawings, there is illustrated in Fig. 1 a block 10preferably smooth and flat and composed of a dark stone, artiicial flintor other suitable substances not subject to acid action.

In Figs. 2 and 3 there is illustrated a testing device, consisting of asleeve 11 having a handle 12 secured thereto and a plurality of bars orarms 13, 14', 15, 16, 17, '18, 19 and 20 pivoted on the sleeve 11. Oneof these bars has an end portion 21 of platinum, and each of the otherbars has an end portion of a platinum alloy of a known composition. Forinstance, the following alloys may be used as standard samples, referredto hereinafter as standardsz Iridium Platinum 90% Platinum 100%Palladium 10% Palladium Palladium Palladium 40% Palladium 8. Palladium100% Marks are made on the block by one or more of the standards and byan article to be tested. These marks are covered by the acid and theblock heated. The heat causes Platinum 90% Platinum 80% Platinum 70%Platinum Platinum 50% -chlorine to be liberated and this dissolves themarks more or less rapidly.

Of the standards above enumerated N o. 1

' will dissolve and disappear slower than No.

2 and Nos. 3, 4, 5, 6, 7 and 8 will dissolve and disappear faster thanNo. 2, each successive sample in the order named dissolving faster thanthe preceding sample. Any one of the eight samples may be com ared withthe sample to be tested and w en a sample has been found to dissolve inthe same time as that of the sample tested, the degree of purity of theunknown sample will be determined.

The acid used for dissolving the samples preferably consists of amixture in equal parts of nitric and muriatic acids. As a loswillliberate chlorine when heated. The

, heat may beV applied to the stone in any suitable Way as by an alcohollamp 25 and the stone should not be heated to a temperature above theboiling point of the acid.

Although one specific embodiment of the invention has been particularlyshown and described, it will be understood that the invention is capableof modification and that changes in the construction and in thearrangement of the various parts may be made without departing from thespirit or .scope of the invention, as expressed in the following claims.

What I claim is:

l. The method of testing platinum alloys which consists in scratchingmarks on a flat stone with the alloy to be tested and with an alloy ofknown composition or with pure platinum, covering the marks with aplatinum dissolving liquid and comparing the rate of speed of the actionof the liquid on the marks.

2. The method of testing platinum alloys which consists in scratchingmarks on a flat stone with the alloy to be tested and with an alloy ofknown composition or with pure platinum, heating the stone, covering themarks with a platinum dissolving liquid and comparing the rate of speedof the action of the liquid on the marks.

3. The method of testing platinum alloysV which consists in scratchingmarks on a block of material not subject to acid action and having asmooth, fiat, dark surface, with the alloy to be tested and with analloy of known composition or with p'ure platinum, covering the markswith a mixture of nitric and muriatic acids, and comparing the rate ofspeed of the action of the acids on the marks.

4. The method of testing platinum alloys which consists in scratchlngmarks on a block of material not subject to acid action and having asmooth, fiat, dark surface, with the alloy to be tested and with analloy of known composition or with pure platiniun, covering the markswith .a liquid from which when heated chlorine is liberated, heating theblock to liberate chlorine, and comparing the rate of speed of theaction of the chlorine on the marks.

5. The method of testing platinum alloys which consists in scratchingmarks on a block of material not subject to acid action and having asmooth, fiat, dark surface, with the alloy to be tested and with analloy of known composition or with pure platinum, covering themarks witha mixture of nitric and muriatic acids, heating the block to liberatechlorine, and comparing the rate of speed of the action of the chlorineon the marks.

6. A device4 for use in testing 'platinum alloyscomprising a pluralityof arms, each arm having its free end formed of a platinum alloy ofknown composition. 'x

7. A device for use in testin platinum alloys comprising a plurality oarms, the free end of one arm being formed of pure platinum and the endsof the other arms being formed of platinum alloys of known composition.

8. A device for use in testing platinum alloys comprising a plurality ofpivoted arms, the free end of one arm being formed of pure platinum andthe ends of the other arms being vformed of platinum alloys of knowncomposition.

In witness whereof, l have hereunto set my hand this 26 day of December,1923.

'ADOLPH coHN.

